Objective: We determined the incidence and predictive factors of difficult airway problems, and the devices used to solve the problems, in patients having general anesthesia.
Methods: We reviewed reported difficult airway cases in 37,805 patients who underwent general anesthesia from May 2011 to October 2013. Data were obtained from a procedural audit system implemented in our institute.
Results and conclusion: There were 885 (2.3%) patients with difficult airway problems. The incidence of difficulty encounter with tracheal intubation, supraglotic airways and mask ventilation were 4.7%, 0.4% and 1.0%, respectively. Of the 805 patients with difficult tracheal intubation, tracheal intubation failed in 11 (0.1%) patients and 3 of these patients needed tracheotomy. The main risk factors of a difficult airway were short thyromental distance (odds ratio 11.3 (9.6-13.4)) and limited neck extension (OR 7.0 (5.5-8.8)). Patients in whom management was anticipated to be difficult had a fourfold higher risk of actual difficulty compared to patients in whom difficulty was not anticipated. The negative predictive value of this simple preoperative evaluation was 98.7%. The most frequently used devices enabling tracheal intubation when difficulty was encountered were bougies and videolaryngoscopes, especially for unanticipated difficulties. Supraglottic airways enabled ventilation and oxygenation when difficult intubation was encountered, but there was a 0.4% incidence with difficult supraglottic airway placement. Our review supports a pre-anesthesia simple airway evaluation, avoiding multiple attempts at tracheal intubation or supraglottic airway insertion when difficulty is encountered and early use of a small and familiar range of alternative methods.